Reference signal pattern

1. A method in a node, comprising: generating a frame structure comprising at least a first subframe, the first subframe comprising a first symbol and a second symbol, each of the first and second symbols comprising a plurality of resource elements, wherein the first symbol carries control information and the second symbol carries a data transmission; reserving one or more of the plurality of resource elements in the first symbol for reference signals, wherein the resource elements reserved for reference symbols comprise a first subset of resource elements that overlap in frequency domain with the data transmission carried in the second symbol and a second subset of resource elements that do not overlap in frequency domain with the data transmission carried in the second symbol; modulating one or more of the first subset of reserved resource elements in the first symbol with reference symbols; and transmitting the at least one subframe to another node.

2. The method of claim 1 , wherein: the frame structure further comprises a second subframe comprising a plurality of symbols; the data transmission carried in the second symbol of the first subframe is a subframe aggregate data transmission that extends in time domain across at least one of the plurality of symbols of the second subframe; and the method comprises communicating information indicating which of the plurality of symbols within the subframe aggregate data transmission contain reference signals.

3. The method of claim 1 , comprising creating multiple orthogonal reference signals far a multiple-input-multiple-output (MIMO) transmission scheme.

4. The method of claim 3 , wherein creating multiple orthogonal reference signals for the MI MO transmission scheme comprises one or more of: using frequency division multiplexing to separate reference signals; using code division multiplexing to separate reference signals; and using orthogonal cover codes between the reserved resource elements modulated with reference symbols in the first symbol and one or more of the plurality of resource elements in the second symbol.

5. The method of claim 1 , wherein: the first and second symbols are orthogonal frequency division multiplexing symbols; and the reference signals comprise demodulation reference signals.

6. The method of claim 1 , wherein the node comprises one of: a network node; and a wireless device operating in a device-to-device scenario.

7. The method of claim 1 , wherein the control information is carried on a Physical Downlink Control Channel and the data transmission is carried on a Physical Data Channel.

8. The method of claim 1 , wherein the first symbol also carries data.

9. The method of claim 1 , wherein the control information is carried in one or more reserved resource elements that are not modulated with reference symbols.

10. A method in a node, comprising: receiving a first subframe comprising a first symbol and a second symbol, each of the first and second symbols comprising a plurality of resource elements, one or more of the plurality of resource elements in the first symbol reserved for reference signals, wherein the first symbol carries control information and the second symbol carries a data transmission; decoding the control information carried in the first symbol; obtaining scheduling information from the decoded control information, the scheduling information indicating a location of the data transmission in frequency domain; determining, based on the location of the data transmission in frequency domain, which of the one or more reserved resource elements in the first symbol are modulated with reference symbols; and performing channel estimation using the one or more reserved resource elements in the first symbol that are modulated with reference symbols.

11. The method of claim 10 , wherein the one or more reserved resource elements in the first symbol that are modulated with reference symbols comprise a subset of the one or more reserved resource elements that overlap in frequency domain the data transmission carried in the second symbol.

12. The method of claim 10 , comprising: receiving a second subframe comprising a plurality of symbols, wherein the data transmission carried in the second symbol of the first subframe is a subframe aggregate data transmission that extends in time domain across at least one of the plurality of symbols of the second subframe; and obtaining information indicating which of the plurality of symbols within the subframe aggregate data transmission contain reference signals.

13. The method of claim 10 , wherein the first subframe includes multiple orthogonal reference signals for a multiple-input-multiple-output (MIMO) transmission scheme.

14. The method of claim 10 , wherein: the first and second symbols are orthogonal frequency division multiplexing symbols; and the reference signals comprise demodulation reference signals.

15. The method of claim 10 , wherein the node comprises one of: a wireless device operating in downlink; a wireless device operating in a device-to-device scenario; and a network node operating in a wireless self-backhaul scenario.

16. The method of claim 10 , wherein the control information is carried on a Physical Downlink Control Channel and the data transmission is carried on a Physical Data Channel.

17. The method of claim 10 , wherein the first symbol also carries data.

18. The method of claim 10 , wherein the control information is carried in one or more reserved resource elements that are not modulated with reference symbols, and decoding the control information comprises: performing decoding as if the control information is mapped around the one or more reserved resource elements in the first symbol; and performing decoding as if the control information is mapped to the one or more reserved resource elements that are not modulated with reference symbols.

19. The method of claim 10 , wherein performing channel estimation using the one or more reserved resource elements in the first symbol that are modulated with reference symbols comprises: decoding the data transmission using the one or more reserved resource elements in the first symbol that are modulated with reference symbols.

20. A node, comprising: one or more processors, the one or more processors configured to: generate a flame structure comprising at least a first subframe, the first subframe comprising a first symbol and a second symbol, each of the first and second symbols comprising a plurality of resource elements, wherein the first symbol carries control information and the second symbol carries a data transmission; reserve one or more of the plurality of resource elements in the first symbol for reference signals, wherein the resource elements reserved for reference symbols comprise a first subset of resource elements that overlap in frequency domain with the data transmission carried in the second symbol and a second subset of resource elements that do not overlap in frequency domain with the data transmission carried in the second symbol; modulate one or more of the first subset of reserved resource elements in the first symbol with reference symbols; and transmit the at least one subframe to another node.

21. A node, comprising: one or more processors, the one or more processors configured to: receive a first subframe comprising a first symbol and a second symbol, each of the first and second symbols comprising a plurality of resource elements, one or more of the plurality of resource elements in the first symbol reserved for reference signals, wherein the first symbol carries control information and the second symbol carries a data transmission; decode the control information carried in the first symbol; obtain scheduling information from the decoded control information, the scheduling information indicating a location of the data transmission in frequency domain; determine, based on the location of the data transmission in frequency domain, which of the one or more reserved resource elements in the first symbol are modulated with reference symbols; and perform channel estimation using the one or more reserved resource elements in the first symbol that are modulated with reference symbols.